If you're getting the Permission denied that's because you are trying to execute the commands as a normal user (not administrator). Normally you would use sudo to execute the commands as administrator but sudo is broken, so you have two choices:- go to the recovery console where you'll boot as root and therefore have permissions to modify sudo- boot from a live cd and mount the partition where your sudo file is, and now you can run the commands over that sudo file using the not broken sudo from the live cd